<!--
 * @Description: 图片上传组件
 * @Author: Neo
 * @Date: 2019-12-11
 * @LastEditTime: 2021-11-17
 * @LastEditors: Neo
-->
<template>
  <div class="uploadWrapper">
    <vuedraggable
        class="vue-draggable"
        :class="{ single: isSingle, maxHidden: isMaxHidden }"
        v-model="imgList"
        tag="ul"
        draggable=".draggable-item"
        @start="onDragStart"
        @end="onDragEnd"
    >
      <!-- 拖拽元素 -->
      <li
          v-for="(item, index) in imgList"
          :key="item + index"
          class="draggable-item"
          :style="{ width: width + 'px', height: height + 'px' }"
      >
        <el-image :src="item" :preview-src-list="[item]"></el-image>
        <div class="shadow" @click="onRemoveHandler(index)">
          <i class="el-icon-delete"></i>
        </div>
      </li>
      <!-- 上传按钮 -->
      <el-upload
          slot="footer"
          ref="uploadRef"
          class="uploadBox"
          :style="{ width: width + 'px', height: height + 'px' }"
          :action=actions
          :headers="headers"
          :data="form"
          accept=".jpg,.jpeg,.png,.gif"
          :show-file-list="false"
          :multiple="!isSingle"
          :limit="limit"
          :before-upload="beforeUpload"
          :on-success="onSuccessUpload"
          :on-exceed="onExceed"
      >
        <i class="el-icon-plus uploadIcon">
          <span class="uploading" v-show="isUploading">正在上传...</span>
          <span
              v-if="!isUploading && limit && limit!==99 && !isSingle"
              class="limitTxt"
          >最多{{ limit }}张</span>
        </i>
      </el-upload>
    </vuedraggable>
  </div>
</template>

<script>
import vuedraggable from 'vuedraggable' // 一款vue拖拽插件
import lrz from 'lrz' // 一款图片压缩插件
import utils from './utils'
import {getToken} from '@/common/token'

export default {
  name: 'ImgUpload',
  props: {
    // 图片数据(图片url组成的数组) 通过v-model传递
    value: {
      type: Array,
      default() {
        return []
      }
    },
    // 限制上传的图片数量
    limit: {
      type: Number,
      default: 99
    },
    // 限制上传图片的文件大小(kb)
    size: {
      type: Number,
      default: 2048
    },
    // 是否是单图上传(单图上传就是已传图片和上传按钮重叠)
    isSingle: {
      type: Boolean,
      default: false
    },
    // 是否使用图片压缩
    useCompress: {
      type: Boolean,
      default: false
    },
    // 图片显示的宽度(px)
    width: {
      type: Number,
      default: 100
    },
    // 图片显示的高度(px)
    height: {
      type: Number,
      default: 100
    }
  },

  data() {
    return {
      form: {cateid: 1},
      actions: process.env.VUE_APP_API + "/apiadmin/uploads/index",
      headers: {
        "Authorization": "Bearer " + getToken()
      },
      isUploading: false, // 正在上传状态
      isFirstMount: true // 控制防止重复回显
    }
  },

  computed: {
    // 图片数组数据
    imgList: {
      get() {
        return this.value
      },
      set(val) {
        if (val.length < this.imgList.length) {
          // 判断是删除图片时同步el-upload数据
          this.syncElUpload(val)
        }
        // 同步v-model
        this.$emit('input', val)
      }
    },
    // 控制达到最大限制时隐藏上传按钮
    isMaxHidden() {
      return this.imgList.length >= this.limit
    }
  },

  watch: {
    value: {
      handler(val) {
        if (this.isFirstMount && this.value.length > 0) {
          this.syncElUpload()
        }
      },
      deep: true
    }
  },

  mounted() {
    if (this.value.length > 0) {
      this.syncElUpload()
    }
  },

  methods: {
    // 同步el-upload数据
    syncElUpload(val) {
      const imgList = val || this.imgList
      this.$refs.uploadRef.uploadFiles = imgList.map((v, i) => {
        return {
          name: 'pic' + i,
          url: v,
          status: 'success',
          uid: utils.createUniqueString()
        }
      })
      this.isFirstMount = false
    },
    // 上传图片之前
    beforeUpload(file) {
      this.isFirstMount = false
      if (this.useCompress) {
        // 图片压缩
        return new Promise((resolve, reject) => {
          lrz(file, {width: 1920}).then((rst) => {
            file = rst.file
          }).always(() => {
            if (utils.validImgUpload(file, this.size)) {
              this.isUploading = true
              resolve()
            } else {
              reject(new Error())
            }
          })
        })
      } else {
        if (utils.validImgUpload(file, this.size)) {
          this.isUploading = true
          return true
        } else {
          this.$message({type: 'error', message: '上传图片大小不能超过'})
          return false
        }
      }
    },
    // 上传完单张图片
    onSuccessUpload(res, file, fileList) {
      if (res.data) {
        if (this.imgList.length < this.limit) {
          this.imgList.push(res.data)
        }
      } else {
        this.syncElUpload()
        this.$message({type: 'error', message: res.msg})
      }
      this.isUploading = false
    },
    // 移除单张图片
    onRemoveHandler(index) {
      this.$confirm('确定删除该图片?', '提示', {
        confirmButtonText: '确定',
        cancelButtonText: '取消',
        type: 'warning'
      })
          .then(() => {
            this.imgList = this.imgList.filter((v, i) => {
              return i !== index
            })
          })
          .catch(() => {
          })
    },
    // 超限
    onExceed() {
      this.$refs.uploadRef.abort() // 取消剩余接口请求
      this.syncElUpload()
      this.$message({
        type: 'warning',
        message: `图片超限，最多可上传${this.limit}张图片`
      })
    },
    onDragStart(e) {
      e.target.classList.add('hideShadow')
    },
    onDragEnd(e) {
      e.target.classList.remove('hideShadow')
    }
  },

  components: {vuedraggable}
}
</script>

<style lang="less" scoped>
/deep/ .el-upload {
  width: 100%;
  height: 100%;
}

// 上传按钮
.uploadIcon {
  width: 100%;
  height: 100%;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px dashed #c0ccda;
  background-color: #fbfdff;
  border-radius: 6px;
  font-size: 20px;
  color: #999;

  .limitTxt,
  .uploading {
    position: absolute;
    bottom: 10%;
    left: 0;
    width: 100%;
    font-size: 14px;
    text-align: center;
  }
}

// 拖拽
.vue-draggable {
  padding: 0;
  display: flex;
  flex-wrap: wrap;

  .draggable-item {
    margin-right: 5px;
    margin-bottom: 5px;
    border: 1px solid #ddd;
    border-radius: 6px;
    position: relative;
    overflow: hidden;

    .el-image {
      width: 100%;
      height: 100%;
    }

    .shadow {
      position: absolute;
      top: 0;
      right: 0;
      background-color: rgba(0, 0, 0, .5);
      opacity: 0;
      transition: opacity .3s;
      color: #fff;
      font-size: 20px;
      line-height: 20px;
      padding: 2px;
      cursor: pointer;
    }

    &:hover {
      .shadow {
        opacity: 1;
      }
    }
  }

  &.hideShadow {
    .shadow {
      display: none;
    }
  }

  &.single {
    overflow: hidden;
    position: relative;

    .draggable-item {
      position: absolute;
      left: 0;
      top: 0;
      z-index: 1;
    }
  }

  &.maxHidden {
    .uploadBox {
      display: none;
    }
  }
}
</style>
